Passive Microwave Fire and Intrusion Detection System Including Black Body and Spectral Emission at the Hydrogen, Hydroxyl and Hydrogen Chloride Lines

ABSTRACT

A passive microwave receiver array, operating in the one meter to sub-millimeter wavelengths range and including an internationally protected range of frequencies of varying bandwidth, may be used for fire and intrusion detection. One or more receiver arrays can be used to provide a plurality of frequency ranges that can be detected. In an interior installation, one or more receiver arrays can be placed inside a wall made of non-metallic substance and capable of passively receiving frequencies at less than 3 GHz. In other embodiments, the receiver and array can be in the form of a hand-held or wearable device. This method and apparatus achieves high performance by exploiting conventional low noise amplification block conversion circuits and provides the detection of thermal signals through clear, smoky, misty, or environmentally untenable conditions as well as the detection of fire and intrusion events via black box or spectral line emission at hydrogen, hydroxyl radical or HCl spectral line emission where an HCl spectral line detector may be mounted on a wall or pole and have line-of-sight view of an intruder or fire.

CROSS-REFERENCE

This application is a continuation-in-part of U.S. application Ser. No.11/931,399 filed Oct. 31, 2007, which claims priority to provisionalU.S. Application Ser. No. 60/944,217, filed Jun. 15, 2007, thedisclosures of which are incorporated by reference into the presentapplication in their entirety.

TECHNICAL FIELD

Aspects described herein relate to a fire and intrusion detection systemusing passive microwave radio reception.

BACKGROUND

Fire and intrusion detection are important for a myriad of reasons. Firecan cause serious damage to property and persons and can even result inloss of life to persons or animals caught in a fire. Additional damagebeyond that caused by flames can be caused by smoke or soot or by waterused to fight the fire. Such damage can result in significant financiallosses—or worse—to the victims of a fire.

Intruders, whether human or animal, also can cause damage to persons orproperty, and so it may be desirable to detect and locate such intrudersto avoid any problems resulting from their presence. In addition, in thecase of a fire, it can be very important to know whether there are anypersons in a burning location and where they are so that fire fighterseither can locate and rescue such persons or, if no one is present, donot need to take unnecessary risks to rescue persons who are notpresent.

Intrusion detection typically involves the emission of electromagneticor sound waves and detecting their reflection from the intruder.Ultrasonic intrusion systems are described in, for example, U.S. Pat.No. 3,986,183 to Fujiwara and many others. Intrusion detection systemsin which a microwave frequency is transmitted and an intruder detecteddue to reflections of the radiated energy are is detected on a frequencyrange proportional to 0.5 GHz to 30 GHz. A passive detector detectsradiation of a heat source in the frequency ranges of 0.5 to 30 GHz,preferably 2 to 20 GHz. The disclosed system also may comprise aplurality of antennae units, each antennae unit being designed for aparticular, different freque described in, for example, U.S. Pat. No.5,576,972 to Harrison; U.S. Pat. No. 5,578,988 to Hoseit et al.; U.S.Pat. No. 5,793,288 to Peterson et al.; U.S. Pat. No. 5,796,353 toWhitehead; U.S. Pat. No. 6,188,318 to Katz et al.; and U.S. Pat. No.6,384,414 to Fisher et al. The systems described in these patents allrequire an active emission of microwave radiation from a source, whichis reflected by the object (e.g., an intruder) to be detected. Forexample, as described in the Harrison '972 patent, known objects orliving entities may provide baseline signatures against which thereflected radiation can be measured. Movement of an intruder can bedetected by use of the Doppler effect, i.e., by measuring a change inthe reflected radiation as an object moves towards or away from thesource of the radiation. In addition, Fisher et al. describes aplurality of passive thermal radiation sensors adapted to transmit aplurality of sensor signals. The apparatus also includes a distancesensor such that the apparatus can collectively reduce false alarm ratesof intruder detection.

EP 1 944 591 A1 describes a method and device for detecting a heatsource through a wall or other obstacle. Thus, the invention does notrequire direct contact between a heat source and a passive antennae.Radiation ncy band.

WO 97/14941 (PCT/CA96/00686) describes a method for remotely determininginternal temperatures through materials by microwave radiation. Inparticular, the method comprises selecting a frequency range wheremicrowave radiation at least partially penetrates the materials,detecting self emitted thermal radiation through the materials for themicrowave frequency range in a target beam of a passive receiver,producing signals proportional to the thermal radiation detected in thetarget beam, remotely scanning the target beam of the passive receiverthrough a target pattern, comparing the signals for different locationsin the target pattern to identify locations emitting higher thermalradiation, and processing the signal to provide an indication ofinternal temperature for the locations emitting higher thermalradiations. The method is useful for search and rescue missions, naturaldisaster prevention and early detection. The preferred frequency rangeis 0.5 to 40 GHz.

FR 2627865 describes a radiometer measurement device that includes anantenna for capturing thermal noise captured by a target. In particular,the radiometer is useful in preventing fires wherein the smoke is thick.The radiometer takes microwave radiation measurements in the band of 34to 36 GHz.

DE 3147775 A1 describes a method for fire detection using a flamedetector to monitor microwave radiation.

Referring to FIG. 19, there is shown a plot of a human body, candleflame, Bunsen burner and sun radiation as a black body. As will befurther discussed herein, a black body radiates frequencies in themicrowave range including a fire and a human body. The depicted graphtends to show relative spectral emission as peaking for a human body inthe infrared range at 104 nanometers in wavelength and frequency. Thegraph also shows that black body radiance from either a flame or a humanbody follows a straight line decline with increasing wavelength anddecreasing frequency into the microwave band from the infrared. Thegraph is extrapolated from FIGS. 2.1 of Three-Dimensional Reconstructionof Fire From Images, by S. W. Hasinoff, thesis prepared for theUniversity of Toronto, Department of Computer Science, 2002. Humansexhibit primarily black body emission. As the graph demonstrates,various fires exhibit black body radiation as well at approximately thesame frequency. Moreover, as will be discussed further herein, fire alsoresults in free radical spectral emission at specific frequencies

Referring to FIG. 20, there is shown attenuation of microwave signals of0.5 to 2.5 GHz measured through various wall materials: drywall, brick,block, adobe and cement taken from FIG. 5 of Image formation throughwalls using a distributed radar sensor network, by Allan R. Hunt, ofAKLELA, Inc., Santa Barbara, Calif., 2005, available from the AKLELA website. As illustrated from the plot, drywall has a magnitude of −5 dB at2000 MHz. Alternatively, concrete has a magnitude of −25 dB at 2,000MHz. Therefore, the attenuation of microwave signals through drywall is5 times greater than through concrete.

Fire protection engineering concentrates on the detection of bothflaming and smoldering fire signatures, typically through the design ofheat, smoke, and optical detectors and combinations of such detectorsand arrays. Flame and radiation detectors can be used to monitor for thepresence of sparks, burning embers and flames. Ultraviolet and infrareddetectors can also be used to detect fire by sensing electromagneticradiation at ultraviolet and infrared frequencies. Thermal sensingdifferentiates a temperature of an object from that of a predeterminedsteady state. For example, U.S. Pat. No. 6,724,467 to Billmers et al.,describes a system and method for viewing objects at a fire scene bydiscriminating reflections from an object from smoke and fire. Somelimited tests also have utilized acoustic sensors for fire detection.

Such techniques, however, are not infallible and frequently result infalse alarms. For example, a thermal sensor in the proximity of abathroom shower may detect rising air temperature from a hot shower andtrigger an unnecessary alarm. In addition, since such thermal detectorsdo not detect smoke, they can be slower to react and detect a fire thanare smoke detectors.

Consequently, thermal sensors are often used in combination with smokedetectors which operate upon the detection of particulate matter fromsmoke in the air. Particle and smoke detectors use photoelectric,ionization, carbon monoxide, gas-sensing, and photo beam technologies tosense byproducts of combustion. However, these devices also are notinfallible, and may falsely trigger from, for example, cigarette orcigar smoke. Moreover, one or both of the thermal and smoke detectorsmay be slow to react to a growing fire, thus leading to greater risk toproperty or life. In addition, the presence of smoke can complicate thedetection of fires. Studies show that 90% of wood smoke particles aresmaller than 1 micron in size. Particles from oil smoke are in the 0.03to 1 micron range, while particles from cooking smoke from grease are inthe 0.01 to 1 micron size, as is tobacco smoke. Consequently,discrimination among types of smoke is difficult, which requiressophisticated pattern recognition algorithms and detector sensors toreduce the nuisance sensitivity (see L. A. Cestari, et al., “AdvancedFire Detection Algorithms using Data from the Home Smoke DetectorProject,” Fire Safety Journal, 40 (2005), 1-28).

Microwave engineering technologies also have been considered as a meansto detect flaming and smoldering fires, particularly when usingmulti-spectral electromagnetic wave sensing. The premise is that thefire's radiant heat transfer components generate a detectable signal inthe microwave portion of the electromagnetic spectrum.

Electromagnetic waves are created when charged particles such aselectrons change their speed or direction. These electromagnetic wavesconsist of an electric field and a magnetic field perpendicular to theelectric field. The oscillations of these fields are reflected in thefrequency and wavelength of the electromagnetic wave. The frequency isthe number of waves (or cycles) per second. The energy of these wavesmay also be characterized in terms of the energy of photons, mass-lessparticles of energy traveling at the speed of light that may be emittedat certain discrete energy levels. The following mathematicalrelationship demonstrates a relationship among the wavelength of anelectromagnetic wave, its frequency, and its energy:

$\lambda = {\frac{c}{f} = \frac{hc}{E}}$

where

-   -   λ=wavelength (meters)    -   c=speed of light (3×10⁸ meters per second)    -   f=frequency (Hertz)    -   h=Planck's constant (6.63×10⁻²⁷ ergs per second)    -   E=energy of the electromagnetic wave (ergs)

Wavelength and frequency are the inverse of one another as related bythe speed of light, and may be used interchangeably herein in thedescription of embodiments and the claims as equivalents of one another.Note that the energy of an electromagnetic wave is proportional to thefrequency and is inversely proportional to the wavelength. Therefore,the higher the energy of the electromagnetic wave, the higher thefrequency, and the shorter the wavelength.

The spectrum of electromagnetic waves is generally divided into regionsor spectra, classified as to their wavelength or, inversely, as to theirfrequency. These bands of wavelengths (frequencies) range from short tolong wavelengths (high to low frequency) and generally consist of gammarays, x-rays, ultraviolet, visible light, infrared, microwave, and radiowaves. The term “microwave” generally is used to refer to waves havingfrequencies between 300 Megahertz (MHz) (wavelength=1 m) and 300Gigahertz GHz (wavelength=1 mm). Microwave radiation is highlydirectional, and the higher the frequency, the more directional theemitted radiation. For the purposes of the present application andclaims, an emission above 300 GHz up to 1000 GHz will also be consideredwithin the microwave band.

The radiation from electromagnetic waves can be emitted by thermal andnon-thermal means, depending upon the effect of the temperature of theobject emitting the energy. Non-thermal emission of radiation in generaldoes not depend on the emitting object's temperature. The majority ofthe research into non-thermal emission concerns the acceleration ofcharged particles, most commonly electrons, within magnetic fields, aprocess referred to in the astrophysics field as synchrotron emission.For example, astrophysicists and radio astronomers look for synchrotronemissions from distant stars, supernovas, and molecular clouds.

On the other hand, thermal emission of radiation from electromagneticwaves depends only upon the temperature of the object emitting theradiation. Raising the temperature of an object causes atoms andmolecules to move and collide at increasing speeds, thus increasingtheir accelerations. The acceleration of charged particles emitselectromagnetic radiation which forms peaks within the wavelengthspectrum. There may be a direct correlation in changes in temperatureimpacting the accelerations of the composite particles of an object withthe frequency of the radiation and peaks within the spectrum. Once anobject reaches its equilibrium temperature, it re-radiates energy atcharacteristic spectrum peaks.

Common forms of this radiation include blackbody radiation, free-freeemission, and spectral line emission. A blackbody is a theoreticalobject that completely absorbs all of the radiation falling upon it anddoes not reflect any of the radiation. Thus, any radiation coming from ablackbody is from its inherent radiation and is not the result of anyradiation incident upon it. Blackbody radiation is a basic form ofthermal emission of electromagnetic radiation from an object whosetemperature is above absolute zero (0 Kelvin). Practical examples ofblackbody radiators include a human body, a Bunsen burner, a candleflame, the sun and other stars in the galaxy.

Passive high-gain directional microwave antennas and receivers have beenused to measure the temperature of a remote object in the technicalfield commonly known as microwave radiometry. Typical users of microwaveradiometry are radio astronomers scanning extraterrestrial objects andthe earth. A microwave radiometer known from the field of the astronomysciences pointed at the sky can produce a measurable voltage outputwhich is proportional to the temperature of the target. For example, thescience of detecting the temperatures of planets is an establishedtechnology in the field of radio astronomy, and radio astronomers canuse microwave apparatus to measure the temperatures of distant planetsand stars. Orbiting satellites pointed back towards the earth may alsouse microwave apparatus to conduct remote sensing of regions of theearth's surface, for example, to detect volcanic activity or to taketemperature readings generally.

Radio astronomy is internationally allocated certain bands offrequencies for research purposes according to the 1979 InternationalTelecommunication Union's World Administrative Radio Conference, alsoknown as “WARC-79,” (J. Cohen, et al., CRAF Handbook for Astronomy,Committee on Radio Astronomy Frequencies, European Science Foundation,3d Ed. (2005)). These bands are free of microwave active transmissionand so are relatively free of noise when used for passive detection, forexample, from the stars or planets. Use of passive microwave frequenciesat these internationally protected frequencies within the microwaveradiation spectra may guarantee that reception is free of interferencefrom active microwave radiation.

Some of the WARC-79 allocated bands are reserved as “PRIMARY exclusive.”These PRIMARY exclusive bands include 21.850 to 21.870 MHz, providing a20 KHz wide band; 1.400 to 1.427 GHz, providing a 27 MHz band; 2.690 to2.700 GHz, providing a 10 MHz band, 10.680 to 10.700 GHz, providing a 20MHz band; 15.350 to 15.400 GHz, providing a 50 MHz band; 23.600 to24.000 GHz, providing a 400 MHz band; 31.3 to 31.5 GHz, providing a 200MHz band; 50.2 to 50.4 GHz providing a 200 MHz band, 86.0 to 92.0 GHzproviding a 6 GHz band; 100.0 to 102.0 providing a 2 GHz band, 114.25GHz to 116 GHz providing a 1.75 GHz band and 116.00 to 119.98 GHzproviding a 3.98 GHz band. The 1.400 to 1.427 GHz band includes thespectral hydrogen line which is very important for radio astronomypurposes. In addition, some bands are labeled as “PRIMARY exclusive” butare restricted according to region of the Earth's surface.

Other frequencies also are set aside and require “Notification of Use”when someone wishes to transmit on these frequencies. These frequenciesinclude 4.950 to 4.990 GHz, providing a 40 MHz band. The 1.6 to 1.7 GHzband is utilized for missile tracking radar but the chances ofinterference in a passive fire detection system would be low. Just aboveis 1.7188 to 1.7222 GHz which is used as a “secondary” “fixed mobile”band and includes the OH or hydroxyl radical. Hydroxyl radical spectrallines within this band are known to each exhibit a narrow and intenseemission line that is especially suitable for measuring Doppler effect.Still other frequencies are “PRIMARY shared with active.” The entireband of frequencies between 275 GHz and 1000 GHz require “notificationof use” but are otherwise unused for any purposes.

In any of these frequency bands, active microwave frequencies present ina passively received signal may be known to a passive receiver so thatthe active frequency can be distinguished and ignored. For example,1.400 to 1.427 GHz provides a protected bandwidth of 27 MHz. Thewavelength of 21 cm. corresponds to a hydrogen line radical. A widerband may be received at an antenna and block converted in the field ofastronomy. Alternatively, the output can be narrowed by a bandpassfilter. Also, conventional low noise amplifiers may pass a band ofinterest and provide gain as will be further discussed herein. Inaddition, passive microwave reception at this frequency range may becombined with reception of microwave radiation at other microwavefrequencies outside this range. Moreover, other microwave frequenciesincluding or overlapping the internationally protected bands may bedetected over wider bandwidths such as 100 MHz to several hundred GHz.

Range resolution is fundamentally limited by the bandwidth of thetransmitted frequency. The change in range resolution, ΔR, is defined bythe equation, c/2*BW, wherein c is the speed of light (˜3*10⁸meter/second) and BW is the bandwidth. Thus, the wider the bandwidth,the better the range resolution. For instance, at 1,500 MHz bandwidth,the range resolution is 0.1 m.

On a similar note, cross range resolution is determined by frequency andthe aperture size of the antennae. At longer distances, larger antennasand/or higher frequencies are necessary to maintain the rangeresolution. For instance, at a frequency of 1 GHz, the range resolutiondecreases with an increasing detection range and decreasing antennaarray aperture size.

Improved devices for microwave detection include, for example, use ofmetal-semiconductor field effect transistors (MESFETs) for low noiseblock converters. Such microwave detection devices are described inseveral U.S. patents, including U.S. Pat. No. 7,052,176 to Stephan etal.; U.S. Pat. No. 5,302,024 to Blum; U.S. Pat. No. 5,370,458 to Goff,and U.S. Pat. No. 6,767,129 to Lee et al. Devices for microwavedetection are presently less expensive when detecting radiation in arange of microwave frequencies less than 25 GHz; however, improvementsin microwave detection circuitry to practical application at higherfrequencies up to the infrared region should not be taken to limitembodiments described herein.

Other technical fields using detection of electromagnetic radiation inthe microwave frequency range include the technical field of cellulartelecommunications. Typical cellular frequencies include 800 MHz and 1.8GHz. Intermediate frequency may be at 70 or 140 MHz. In the cellulartelecommunications field, it is conventional to provide an antenna poleor mount on a building or other fixed structure having some height. Forexample, FIG. 8 of U.S. Pat. No. 5,724,666 to Dent shows a plurality ofantenna arrays 210, 212, each having respective amplifiers 216, whereineach array appears as a plurality of directional elements 224 which maybe used for transmitting and receiving.

The use of passive microwave detection in the field of radio astronomyis described in several U.S. patents, including U.S. Pat. No. 4,499,470to Stacey; U.S. Pat. No. 4,645,358 to Blume; U.S. Pat. No. 5,526,676 toSolheim et al.; and U.S. Pat. No. 6,729,756 to Sezai. The '470 patent toStacey describes a satellite over the oceans of the Earth, their mappingas the satellite passes between land and water and monitoring of thetemperature of the ocean below. The '358 patent to Blume describes aproblem in the radio astronomy field that measurement of the Earth'ssurface properties and those of the universe can be very inaccurate,especially in cases of low contrast with the background and describes aRaleigh-Jeans approximation procedure for overcoming such problems. The'676 patent to Solheim et al. describes principles of microwaveradiometry especially applicable to detection of water vapor and cloudmasses using frequencies, for example, at 50-70 GHz, 19-29 GHz and 40-80GHz. The '756 patent to Sezai discusses use of a deep space referencetemperature of 2.70 Kelvin as well as a hot calibration source.

The principles of radio astronomy also have been applied to measuringenergy inside a human body. Such use can be seen in, for example, U.S.Pat. No. 4,416,552 to Hessemer, Jr. et al.; U.S. Pat. No. 4,532,932 toBatty, Jr. (tumor cells); U.S. Pat. No. 4,583,869 to Chive et al. (useof two probes); U.S. Pat. No. 4,605,012 to Ringeisen et al.(hyperthermia); U.S. Pat. No. 5,677,988 to Takami et al. (internaltemperature of human body); U.S. Pat. Nos. 4,715,727 and 6,932,776 toCarr (heating at 915 MHz and measuring at 4.7 GHz); U.S. Pat. No.4,798,209 to Klingenbeck et al. (diseased human tissue); U.S. Pat. Nos.5,176,146 to Chive and 5,688,050 to Sterzer et al. (mammography); U.S.Pat. No. 6,543,933 to Stergiopoulos et al. (the skull); and U.S. Pat.No. 6,773,159 to Kim et al., U.S. Pat. No. 7,121,719 to Lee et al. andU.S. Pat. No. 7,197,356 to Carr (microwave catheter).

Microwave engineering technologies have also been investigated for usein detecting flaming and smoldering fires. In research by the inventors,fire has been demonstrated to actually be “plasma,” a phenomenon oftenreferred to as the fourth state of matter. Plasma is an ionized gas thatconsists of a mixture of electrons (negatively charged particles) andions (atoms that have lost electrons, resulting in a positive electriccharge). Fire can be easily classified as plasma, because it oftenbehaves like a gas, can conduct electricity, and is affected by magneticfields. Common examples of a plasma fires range from the Sun to the arcformed during electric arc welding, both of which can offer a broadelectromagnetic spectrum of radio interference.

Detection of fires by microwave engineering techniques relies upon thefact that thermal radiation from fires generates a detectable signal inthe microwave portion of the electromagnetic spectrum which, like themicrowave radiometer, can create a measurable change in voltage outputwhich is proportional to a temperature.

For example, one use of microwave technologies in the field of firedetection appears in a 1995 National Institute of Standards andTechnology (NIST) report by Grosshandler entitled, “A Review ofMeasurements and Candidate Signatures for Early Fire Detection,” NISTIR5555, January, 1995 at pp. 13-14. The NIST report suggests that theconcept of multi-spectral electromagnetic wave sensing may be applicableto fire detection. The report cites a “modified microwave motiondetector . . . for monitoring the presence of a flame within amulti-burner natural gas furnace,” citing Berman et al. (1992). (C. H.Bermann et al., “Microwave Backscattering Fuel/Air Ratio Control andFlame Monitoring Device,” Fossil Fuel Consumption, American Society ofMechanical Engineers, Vol. 39, Book G00645, 1992). Moreover, FIG. 2provides data for fire temperature versus existence of fire products atvarious temperature ranges. In particular, CO₂, H₂O, SO₂ and HCldominate across the entire temperature range of a typical fire. Ofthese, H₂O vapour emits microwave at 22.235 GHz, 183.31 GHz, 547.676 GHzand 556.936 GHz. HCl emits a spectral line at 625.040 and 625.980 GHzrespectively according to the CRAF Handbook for Radio Astronomy, 2005,pp. 90-92. Carbon monoxide, H₂, and NO are formed in moderate levels forfire temperatures of about 1500° K. CO emits at 109.782, 110.201,112.359 115.271, 219.560, 220.399, 230.538, 345.796, 439.088, 461.041and 576.268 GHz among other spectral frequencies. Nitric oxide (NO) hasa spectral line at 150.4 GHz. Similarly, the free radicals H, O, OH(hydroxyl), Cl and SO appear at these high fire temperatures. The OHradical appears at frequencies of 1.612231, 1.665402, 1.667359 and1.720530 GHZ and, as indicated above, provides narrow, tall spectrallines, useful for Doppler effect detection.

According to U.S. Pat. No. 5,785,426 to Woskov et al., a waveguide maybe disposed within a furnace to direct radiation through a window to aheterodyne receiver disposed outside the furnace; this radiation can beused to measure furnace temperatures where the microwave radiation is inthe range of 130-140 GHz and converted to 0.4-1.5 GHz for detection.U.S. Pat. No. 5,829,877 to Baath describes utilizing microwave energyand, as shown in FIG. 5 of Baath, describes detecting certain relevantpeaks, for example, SO₂, NO₂, H₂O, and NH₃, among other compounds knownas products of combustion.

Another use of microwave technology can be used to detect moving objectstravelling at relatively fast or slow velocities which emit heat. Earlydetection can be used as a cautionary measure to ward off unnecessarydisasters. Some examples include burglaries, catastrophic events andfires. The flicker, shedding or puffing frequency of fire, for example,can be used as a fire signature and measured for various fires between 0Hz and 30 Hz.

A German 2001 NIST paper suggests that Daimler Chrysler Aerospace AGconducted earlier experiments in fire detection using microwave energy(T. Kaiser et al., “Is Microwave Radiation Useful for Fire Detection?”Proceedings of the 12^(th) International Conference on Automatic FireDetection, AUBE '01, Volume 965, Mar. 26-28, 2001, Gaithersburg, Md.,NIST Special Publication). The purpose of these experiments, which isnot further explained, was to detect fires in garbage bunkers. Thepossibility of using microwave engineering technologies in passive firedetection is also described in the NIST Conference paper in 2001 byKaiser et al. which further describes the use of microwaves to passivelydetect a fire using a conventional Dicke switch operated at 1 KHz tocompare a reference temperature of a room wall with measurements at 11GHz in the microwave region and a bandwidth of 1 GHz. (See R. H. Dicke,“The measurement of thermal radiation at microwave frequencies,” Rev.Scl. Instr. Vol. 17, pp. 268-275, 1946). The discussed technique reliesupon thermal radiation from fires generating a detectable signal in themicrowave portion of the electromagnetic spectrum. To do so, Kaiser etal. further suggest use of a commercial satellite dish and asuperheterodyne low noise converter to measure the microwave radiationof a target test fire.

Follow-up tests are described by Kempka et al. in 2006, and expand thefrequency range of the initial Kaiser et al. experiments from 2 to 40GHz (T. Kempka et al., “Microwaves in Fire Detection,” Fire SafetyJournal, Volume 41, 2006, pp. 327-333). According to this 2006publication, thermal radiation may be measurable utilizing fourbroadband antennas to cover four separate frequency bands of operation,i.e., 2-12, 12-18, 18-26, and 26-40 GHz bands of operation andrespective bandwidths at 100 MHz each. “For each configuration onesample will be measured in the first frequency band. Then the receiverchanges to the next frequency band and takes another sample. After allthe selected frequency bands are measured, the receiver will measure thefirst band again.” Kaiser et al. further suggest using a “hot load”having a temperature of 100° C. (373 K) to calibrate their apparatus ata reference temperature. Certain fires were detected 90 seconds afterignition while another type of fire was detected 80 seconds after aheater was switched on. The time difference between samples was about3.5 seconds.

All United States and foreign patents and articles whose citations areprovided above should be deemed to be incorporated by reference as totheir entire contents for the purposes of understanding the underlyingtechnology behind a passive microwave fire and intrusion detectionsystem.

SUMMARY

This summary is intended to introduce, in simplified form, a selectionof concepts that are further described in the Detailed Description. Thissummary is not intended to identify key or essential features of theclaimed subject matter, nor is it intended to be used as an aid indetermining the scope of the claimed subject matter.

Embodiments of a low-cost passive microwave receiver and associatedarrays in accordance with aspects and features described herein canpermit the efficient monitoring, detection, and reporting of fire andsources of other thermal signatures introduced within a surveillancearea or field of view. In other embodiments, a passive microwavereceiver can be used to recognize human or other animals present in anarea, and thus can be used, for example, as an intrusion detectiondevice based primarily on black body spectrum emission measurement andcomparison with predicted data (for example, per FIG. 19 which may beutilized as a look-up table for frequency or wavelength versus expectedmicrowave black body emission level. An associated fire or intrusiondetection method such as is described herein is passive in nature, andpotentially harmful-to-human and noisy microwave radiation emission maybe limited, with no damage to structures or living organisms as mayoccur from an active microwave radiation system and method.

A passive microwave radiation receiver in accordance with aspectsdescribed herein may comprise a fixed or moveable array of antenna andlow noise receivers mounted in a surveillance grid for an enclosed spaceor an open area. The fixed array of receivers may comprise directionalantennae operating at fixed frequencies over a bandwidth of frequencies,for example, a bandwidth that is protected internationally for passivemicrowave reception. In another embodiment, a passive microwave fire orintrusion detection apparatus may comprise a unit which may be worn orcarried by a person or mounted to a vehicle. A plurality of such passivemicrowave devices may protect a space such as a building or a parkinglot and may monitor for intrusion at openings such as doors and windows.All such devices may be connected to a central computer processingsystem including memory and a display. The memory may store known blackbody emission characteristics for, for example, humans and fires as wellas expected microwave spectral line emission data for fire (for example,HCl, OH and H) as well as Doppler effect intruder and firecharacteristics and shedding frequency fire characteristics. Moreover, asingle reference detector may be used to provide a reference ambienttemperature for operation, for example, one mounted in afloor/ceiling/wall requiring no power to produce a referencetemperature. A passive microwave fire and intrusion detection method andsystem may achieve a high performance including a low level of falsealarms by recognizing known anomalies and exploiting the naturaldetection of thermal signals through clear, smoky, or misty conditions.Moreover, embodiments using improved passive radiometer circuits andprocesses can improve the detection of fire to a matter of seconds fromignition.

Various embodiments in accordance with aspects described herein canprovide a wide range of fire and security applications, including butnot limited to fire detection, proximity and intrusion detection,surveillance, infrastructure protection, and security investigations.For example, low-cost, hand-held microwave detectors may be useful forfire investigators conducting on-scene assessments of post-firesmoldering debris. Passive microwave detectors in accordance with one ormore aspects herein could also assist fire investigators to identify andconfirm multiple sources of ignition during full-scale fire tests,particularly during the generation of optically dense smoke and flames.The intrusion detection aspects herein can also assist fireinvestigators and first responders to identify and locate the presenceof persons or other living beings needing rescue in a fire. In addition,the intrusion detection aspects herein can be used for general securityand monitoring purposes as well.

Significant tests conducted by the inventors have expanded the initialreported results, have demonstrated methods to reduce interference byuse of selected frequencies and isolation of spurious electromagneticnoise, and have introduced new concepts beyond fire detection tointrusion and security alerting. The inventors have presented andpublished their research findings based on these and other tests at the2007 Interflam international engineering meeting and symposium (D. J.Icove and C. Lyster, “Microwave Fire Detection: A Survey andAssessment,” Interflam2007, University of London).

There are a broad range of examples that demonstrate a long-felt needwhere microwave fire and intrusion technologies can play an importantrole, particularly when such a system is fully automated.

For example, in broad surveillance to guard against forest fires, manyof which can quickly burn valuable timber and threaten human life,passive microwave early detection technology would be of extremebenefit. Due to the geometric growth of uncontained forest fires,proactive early detection is highly desired so that a fire can berapidly and aggressively extinguished before it becomes uncontrollable.

The military also could use passive microwave fire and intrusiontechnologies in their support and security efforts, for example, tomonitor and protect battlefields, bridges, harbors, borders,international crossing points, and other critical infrastructures.Another benefit of these technologies is that it can passively detectaircraft coming over the horizon at any altitude.

In addition, domestic fanning activities could benefit from passivemicrowave fire and intrusion detection. Since the technique is alsosensitive to body temperatures within the field of view of the receivingantennae, the tracking and corralling of livestock such as cattle overranges, entering corrals, and even wandering outside boundaries could bebeneficial, particularly for those in the milking industry. Thistechnology could also determine thermal signatures of livestock, humans,or predators so that such animals can be monitored and undesiredintruders identified.

Microwave fire and intrusion detection capabilities can also be used todetect the movement of vehicles along roads and tunnels and shipboardmovements along channels. Signature analysis could identify the trafficflow and thermal signatures differentiating between cars, trucks,motorcycles, and other vessels. This technique could also identifystalled vehicles or those catching fire particularly in high densityunderground tunnels.

These and other uses can be made of a passive microwave fire andintrusion detection method and apparatus in accordance with aspects andfeatures discussed below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an integrated passive fire and intrusiondetection system according to one or more aspects described herein.

FIG. 2 is an exemplary array of microwave receivers and antennas placedin an enclosed space in accordance with one or more aspects describedherein.

FIG. 3 is a block diagram of an exemplary array of microwave receiversand antennas placed in an out-of-doors space in accordance with one ormore aspects described herein.

FIG. 4 is a block diagram of an exemplary array of microwave receiversand antennas placed near a boundary to be protected in accordance withone or more aspects described herein.

FIG. 5A depicts an exemplary embodiment of a wearable apparatuscontaining a passive microwave receiver and antenna array in accordancewith one or more aspects described herein. FIG. 5B depicts an exemplaryembodiment of a handheld apparatus containing a passive microwavereceiver and antenna array in accordance with one or more aspectsdescribed herein.

FIG. 6 depicts an exemplary embodiment of a multi-sided apparatuscontaining multiple passive microwave receiver and antenna arrays inaccordance with one or more aspects described herein.

FIG. 7 depicts an exemplary embodiment of a superheterodyne receiverwith signal display that can be used with a passive fire and intrusiondetection system according to one or more aspects described herein.

FIG. 8 is a schematic of an exemplary passive microwave heterodynereceiver which can be used in an individual antenna array such as thearray shown in FIG. 2.

FIG. 9 is a photograph depicting use of a light source to aim a passivemicrowave receiver in accordance with one or more aspects onto alocation of a test fire during experimental testing described herein.

FIG. 10 is a photograph depicting use of a passive microwave receiveraccording to one or more aspects herein with a flaming test firecomprising burning shredded paper in an enclosed space.

FIG. 11 is a photograph depicting use of a passive microwave receiveraccording to one or more aspects herein with a test fire comprisingburning Isopropanol on a pan.

FIG. 12 is a photograph depicting use of a passive microwave receiveraccording to one or more aspects herein with a smoldering test firecomprising burning shredded paper in an enclosed space.

FIG. 13 is a photograph of a shielded steel building used during testsof a passive microwave fire and instruction detection apparatus inaccordance with one or more aspects described herein.

FIG. 14 is a photograph of a fire test conducted during ignition of afire within the shielded steel building shown in FIG. 15.

FIG. 15 depicts an exemplary set of voltage readings output from thefire test conducted within the shielded steel building shown in FIG. 13.

FIG. 16 depicts time-varying thermocouple temperature readings atapproximately 2 feet (0.61 meters) above the floor level overlaid withthe voltage output readings from the fire test conducted within theshielded steel building shown in FIG. 13.

FIG. 17 depicts an exemplary set of voltage readings output from anintrusion detector due to the presence of an approaching overheadaircraft in accordance with one or more aspects described herein.

FIG. 18 depicts another set of voltage readings output from an intrusiondetector due to the presence of a human at 25 and 50 feet in accordancewith one or more aspects described herein.

FIG. 19 provides a graph providing relative black body spectral emissionversus decreasing frequency/increasing wavelength for the sun, a Bunsenburner, a candle and a human body.

FIG. 20 provide a graph of measured attenuation of microwave frequenciesbetween 0.5 and 2.5 GHz for drywall, brick, block, adobe and cement.

FIG. 21 provides in FIG. 21(A) an exemplary embodiment in which a givenspectral line such as at 21 cm for hydrogen is captured and its Dopplereffect determined as well as its so-called shedding, flicker or pufffrequency at 0-30 Hz; in FIG. 21(B) an exemplary embodiment is providedwhich may take an entire captured passband of black body emission of ademultiplexed passive microwave channel and detect at frequencyincrements of, for example, 3 MHz for continuous attenuation across theentire band as predicted by, for example, FIG. 19.

DETAILED DESCRIPTION

The aspects summarized above can be embodied in various forms. Thefollowing description shows, by way of illustration, combinations andconfigurations in which the aspects can be practiced. It is understoodthat the described aspects and/or embodiments are merely examples. It isalso understood that one skilled in the art may utilize other aspectsand/or embodiments or make structural and functional modificationswithout departing from the scope of the present disclosure.

As described above, it is known that fire, including non-flaming firessuch as smoldering embers, emits a wide spectrum of electromagneticradiation. Such radiation includes not only infrared (heat) radiation,but also includes microwave radiation in the range of 300 MHz to 1000GHz and at corresponding wavelengths of from 1 meter to less than 1 mm,due to the energy radiated by such fires as black body emission andspectral line emission caused by the high energy (temperature) levels ofa fire. Such microwave radiation can be detected without the need forany corresponding emission of microwave radiation by an antenna.Instead, in accordance with aspects and features described herein, theemitted energy of a fire in the microwave regions of the electromagneticspectrum can be detected using passive microwave detection by one ormore antennae.

In addition, living bodies such as persons or animals also emitmicrowave radiation due to their inherent thermal energy via black bodyemission. This radiation also can be detected by the same antenna usedto detect the microwave radiation from a fire.

Thus, a passive microwave detection method in accordance with aspectsdescribed herein can rely upon the fact that thermal radiation fromfires, persons, or other bodies can generate a detectable signal in themicrowave portion of the electromagnetic spectrum.

Embodiments described herein can use characteristics of microwaveradiation at various frequencies in a method and system for fire andintrusion detection. Because of the high frequency/short wavelengthnature of microwaves, microwave radiation can penetrate optically thicksmoke and water vapor, as molecules suspended in the air such as oxygen,water vapor, dust, and smoke do not attenuate the microwave radiationemanating from an object, whether the source of the radiation is athermal incident such as a fire or an intruder or other object.

Passive microwave detectors thus could assist fire fighters to identifyand confirm multiple sources of ignition, particularly in firesinvolving the generation of optically dense smoke. Using well-knownprinciples regarding directionally diverse antennae, a passive microwavedetection system in accordance with aspects herein can permit a fire oran intruder (or fire victim) to be more quickly located and pinpointed.In addition, since radiation is emitted at certain pre-determinedspectral line wavelengths, for example, hydrogen, hydroxyl radical,hydrogen chloride, silicon dioxide or nitrogen dioxide, ammonia, water,carbon monoxide or other detection spectra may be identified, especiallyif present in substantial quantity, so that fire fighters can be awareof the presence of such materials, for example, poisonous materials anddirect their efforts accordingly.

In addition, due to its relatively long wavelength, microwave radiationcan penetrate non-metallic walls, and can thus be used to detect a fireor an intruder within such a non-metallic structure.

FIG. 1 is a block diagram of one embodiment of an exemplary microwavefire and intrusion detection system according to one or more aspectsdescribed in more detail herein. As shown in FIG. 1, a microwave fireand intrusion detection system can include a plurality of detectorarrays, such as detector arrays 1001 a through 1001 d in the exemplaryembodiment shown in FIG. 1, plus reference array 1003. As discussed inmore detail herein, detector arrays 1001 a-1001 d are configured todetect radiation in one or more frequency bands in the microwave range,such as black body radiation emanating from a fire or an intruder andspectral line emission from a fire. Reference array 1003 is configuredto detect radiation from a baseline radiation source such as the groundor a constant temperature hot source. Each detector in array 1001 a-1001d can detect a unique temperature reading indicated by a relativevoltage level output at a given microwave frequency or band offrequencies or be otherwise indicative of the temperature of a firebased on the received microwave radiation, where each detector mayoperate at a different wavelength or frequency or frequency range so asto capture black body or spectral line emission and detect Dopplereffect transitions of an expected frequency and/or fire shedding(sometimes called flicker or puff) frequency (typically a low frequencysuch as 0-30 Hz indicative of a measurement at a microwave frequencyover time). Each array can report this unique temperature reading in theform of a voltage signal that may be sampled by analog to digitalconversion as may be the received frequency value and is in turn outputto a central processing unit comprising a signal processor 1005 andmemory 1013 as shown in FIG. 1 (described in more detail below withrespect to FIGS. 7 and 8). One exemplary digital signal processor foracting on digitally sampled frequency and level measurements is theMotorola DSP56800 which may provide a Doppler input to a moresophisticated data processing apparatus such as a personal or mainframecomputer. The voltage signal level at a given frequency or frequencyrange reported by each detector to signal processor 1005 can be directlyor indirectly proportional to the temperature measured by the detector.Moreover, a spectral line indicator such as the presence of a givenmeasurement of a given radical such as hydrogen or the hydroxyl radicalmay be an indicator of a very high temperature. In an alternativeembodiment, active microwave signals used in a geographic region for,for example, telecommunications, satellite television, or militarypurposes, may be detected, stored in memory 1013 as a signature, andsubtracted as noise from any signals processed by signal processor 1005.

Signal processor 1005 can be in the same or a different location as theantenna arrays, and the signals from each array to signal processor 1005can be transmitted by wired or wireless means. An antenna 1005 a isintended to represent receipt of wireless signals, for example, receivedfrom a vehicle or human investigator to be discussed later withreference to FIG. 5 as well as from fixed or stationary detectors 1001 ato 1001 d. If transmission by wireless transmission, each suchwirelessly transmitted signal from a passive microwave detector can alsoinclude a data signal uniquely indicative of the location and frequencyor frequency range and bandwidth detected so that the signal can beappropriately identified and processed. For example, signal processor1005 can be at a remote location such as a fire station or other centralmonitoring station not affected by inclement environmental conditionssuch as those that may be present at a fire site, fire testing facility,battlefield, hazardous waste dump, or other site.

Once the signals from detector arrays 1001 a-1001 d and reference array1003 are processed, the results can be provided in a number of ways.According to aspects described herein and as discussed below thereceived microwave radiation can be converted into a signal wherein avoltage can be determined as a result of the differences in radiationdetected. In some embodiments, the radiation detected is compared tobaseline radiation from, for example, a floor of a room, the ground, orthe foliage of large trees, and a voltage difference can be used todetect the presence of a fire or an intruder. For example, a positivevoltage is indicative of a fire or high temperature while a negativevoltage may indicate the presence of a human body intruder. In otherembodiments, the baseline radiation can be from a fire itself, anddetected radiation can be used to determine the presence or absence of ahuman or other living being in a burning space via black body radiationprinciples, thus aiding first responders in identifying the presence—orjust as importantly, the absence—of persons in need of rescue. Thefrequency of a spectral line from an excited particle such as a smokeparticle or from the heat of the flame of a fire can result in Dopplereffect or movement of a given spectral line. The spectral line and itsfrequency shift from a predicted value may be used to identify a fire,for example, that of the hydrogen chloride spectral line that is seen atall fire temperatures. Moreover, a shedding frequency may be used as afire flame signature measured, for example, between 0 and 30 Hz.

In some embodiments, the difference in microwave frequencies detected bydetector arrays 1001 a-1001 d and reference array 1003 can be output asa temperature detected by the detector arrays, either as an absolutetemperature or as a temperature difference so that a flaming fire orother thermal event, such as a smoldering fire in the pre-flaming stage,can be detected. Both fires and intruders have predictable black bodyemission, for example, per FIG. 19. Also, the hotter the fire, the moreblack body emission at a given frequency. In addition, as describedabove, in some circumstances, the constituents of the fire or smoke canalso be detected by their spectral line emissions so that fire fighterscan know from the outset what may be burning and can plan for fightingthe fire accordingly. Alternatively, the difference in detectedfrequencies from predicted values can be output as a detection of anintruder and an appropriate alarm can be sounded. Moreover, a visualdisplay may be associated with processor 1005 to provide a visualindication of a black body (fire or intruder presence) or the output maytake the form of a spectral line or frequency display of emission levelversus frequency.

In other embodiments, the central processor 1005 can be connected to aremote or local display so that a visual display of a fire configurationcan be shown, either alone or, for example, combined with an infrared orvisible light display of the burning building captured by an appropriatecamera for storage or retrieval from memory 1013. Such a display outputfrom a passive microwave receiver can show the location of both visibleactively burning fires and less visible non-flaming, non-smoking hotspots. In addition, the intrusion detection aspects of such system canshow the location of any persons or animals within a building, trying toenter or leave a building or other protected space, thus enabling firefighters or other first responders to better focus their efforts tofighting the fire and saving the lives of fire victims without riskingtheirs in unnecessary rescue attempts.

These and other aspects will be discussed in more detail below.

As noted above and as described in more detail herein, aspects of apassive microwave fire and intrusion detection method and apparatus canincorporate the use of one or more passive microwave-based sensorsincluding one or more antennas configured to receive microwave radiationin the microwave frequency range, including any of the several frequencyranges described above that are protected for passive microwavedetection in the field of radio astronomy with detection occurring overthe protected band or those bands such as above 275 GHz not typicallyused for any radio communication or transmission. The present system maybe used in conjunction with other known systems such as ionization,radiation (for example, in the visible or infrared or ultravioletspectrum), smoke and other known detectors. As such, with greaterinformation about a given event, potentially false alarms may beinvestigated thoroughly and eliminated as truly false.

In accordance with one or more aspects described herein, a passivemicrowave fire and intrusion detection system and method can utilize thedetection of microwave radiation on one or more of these protectedfrequencies by various combinations of microwave receivers and antennaarrays. An antenna array in accordance with one or more aspects hereincan be designed to detect a subset of the microwave radiation band offrom, for example, a 27 MHz-wide band of 1.400 to 1.427 GHz for hydrogenline spectral emission at 21 cm and a 20 MHz wide band at a centerfrequency of 10.690 GHz to show an increasing black body emission withincreasing frequency (decreasing wavelength). The principle may beextended to all frequencies across the microwave spectrum and into theinfrared spectrums for black body radiation from a fire or intruder incomparison with expected values as per FIG. 19. In addition, inaccordance with aspects herein, this bandwidth can be split into manydifferent internationally protected bands of varying bandwidth accordingto WARC-79 radio astronomy allocations, with each of a plurality ofreceivers receiving a subset of the emitted black body and spectral linepassive microwave radiation. As other bands may be reserved in thefuture for passive detection, such frequencies and bands may also comewithin the scope of an embodiment. In addition, other bands in themicrowave regions may be utilized, including bands which overlapinternationally protected bands and known microwave radio frequencies ina given area subtracted or filtered from received results in a mannersimilar known from, for example, echo cancellation techniques from thetelecommunications arts.

Due to the mass production of commercial microwave antennas andassociated electronics, the cost of passive microwave fire and intrusiondetection is relatively low when compared to other technologies, such asinfra-red thermal imaging. Low noise amplifier circuitry is nowconventional and provides excellent low noise performance and permitsdiscrimination from noise using antennae that are not high gain or largein size, such as small parabolic or horn antennae.

Antenna arrays in accordance with aspects herein can include flatarrays, parabolic arrays or horn type arrays and can include one or morepoint antenna as well as directional cellular telecommunication poleantenna arrays of antenna elements. For example, in experiments by theinventors and as seen in FIGS. 9-12 and 14, a parabolic dish antennahaving a diameter of approximately 19 inches was used. The antennas usedby the microwave receiver can be smaller of any configuration, however,including fixed, rotational, or steerable antennas, and can be designedin accordance with the bandwidth to be detected. For example, ifsteerable antennas are used, such antennas can be either mechanically orelectronically steered to detect directional beams. Other antenna arrayscould include wide or narrow beamed configurations or lobes, dependingupon the specific design of the individual application, field of view,and property to be protected. In addition, in some embodiments asdescribed below, one or more antenna for passively detecting microwaveradiation from a fire or an intruder can be incorporated into ahand-held device (FIG. 5) that can be carried, for example, by afirefighter, or into a device that can be worn, for example, as part ofa firefighter's helmet or other protective gear. Moreover, a passivemicrowave device may be incorporated into a vehicle or robot which maybe guided from central processor 1005 to monitor a protected space.

An exemplary antenna array may be similar to that depicted in FIGS. 6and 7 of U.S. Pat. No. 5,563,610 to Reudink. Such an array may receivemicrowave frequencies via a first element provided with a low noiseamplifier circuit such as, for example, a model RAS-1420 LNA providing28 dB of gain in the 1.420 to 1.427 GHz 27 MHz pass band of interest,available from www.radioastronomysupplies.com. A second or the sameantenna element of the same array may receive microwave frequencies inthe 1.200-1.900 GHz band including the 1.420 to 1.427 GHZ band ofinterest for hydrogen line and black body emission of passivefrequencies, for example via a ZHL-1217HLN circuit having 30 dB of gainavailable from www.minicircuits.com to capture both hydrogen andhydroxyl spectral emission as well as black body emission at thispassband. A third low noise amplifier choice can be an amplifier such asa ZGL-2700 MLNW, providing 25 dB of gain in the 2.2 to 2.7 GHz bandincluding a 2.690 to 2.700 GHz providing a 10 MHz band of interest. Thisthird LNA may have its own antenna element or share an antenna elementof the same array. When overlapping bands with protected microwavepassive frequency bands are captured, any active frequencies may befiltered out using band stop filters so that only the desired passivefrequencies are analyzed by the signal processor or, vice versa, afilter may be designed to pass the band of interest. Moreover, theprotected frequency is received with no active radio interference andthus, even the smallest of measure values can be detected and analyzedwith a high true desired signal to noise ratio.

In accordance with aspects herein, for any antenna array or antennaconfiguration, it can be desirable to calibrate an antenna using areference target having a known temperature to provide a baselinereference temperature and a reference received energy level via areference array 1003 of FIG. 1. One such method for calibration caninvolve using a Dicke switch method to compare the detected radiationwith a known temperature source. Typical frequencies of operating aDicke switch may be from 1 Hz to 10 KHz, with a conventional range beingfrom 100 Hz to 1 KHz. A reference temperature can be provided by using a“hot load,” for example, an object having a fixed temperature of 100°C., and the microwave radiation emanating from that object can bemeasured to use as a baseline reference. Alternatively, a known orambient temperature such as that of a human body or a relatively stabletemperature such as that of the ground, foliage, the sun and the likeprovide optional reference temperatures which require no power togenerate.

Other reference temperatures can be used depending on the configurationand application of the antennae. Various calibration sources fortemperature already exist in the environment, both inside and out andnaturally vary depending on the time of day and weather. For antennaethat are worn or hand-held or moveable of a vehicle, the human body(skull or chest cavity) or vehicle temperature may provide anappropriate reference temperature. In indoor installations, the wall orfloor may be used as a suitable temperature reference source. In anoutdoor installation, the ground can be used as a source of baselinereference energy because of its predictable temperature variance in viewof time of day and weather conditions. Other outside references fortemperature, for example, could include the temperature of the sun, theearth, or foliage of large trees. Each of these may be used to establisha reference temperature and a reference received energy level for thesurrounding environment via a detector 1003. In addition, a calibrationroutine conducted over a period of time in a fixed system may recordknown objects such as vehicles or aircraft and the presence andintrusion of pet animals and other living organisms expected to bepresent. These calibration techniques may result in a known passivemicrowave image for storage in memory 1013 for subtraction from laterreceived passive microwave readings taken in the presence of a fire orintruder.

FIGS. 2-6 depict system embodiments for various exemplary applicationsof arrangements of antenna arrays that can be used in a passivemicrowave fire and intrusion detection system and methods in accordancewith one or more aspects described herein. It should be noted that theconfigurations shown in FIGS. 2-6 are exemplary only, and that otherconfigurations and uses of passive microwave antenna arrays can be madewithin the scope of the present disclosure. The antennas may be close toor far away from the target source of the black body or spectral linemicrowave radiation, whether it is a fire or an intruder. For example,in some embodiments, the antennas can be located as close as 2.5 metersand as far as 100's of meters from the target in a protected space,although, as discussed below, the target may be much farther away, sinceusing the methods and apparatus described herein, an airplane (or aforest fire) can be detected at thousands of meters distance.

FIG. 2 depicts an exemplary array of antennas that can be used in aninterior installation, for example, to protect an enclosed space. Spacesthat can be protected by such a configuration include commercial andresidential buildings, offices, warehouses, and other structures.

As shown in FIG. 2, a plurality of detector antenna arrays 2001 a-2001 fcan be placed at spaced-apart locations around a perimeter of anenclosure 2009 where passive detectors 2001 a-d are mounted in or on awall surface pointing inward and detectors 2001 e-f are protectingopenings such as doors, gates, windows and the like. In an exemplaryembodiment, each detector antenna array can be in the form of a cellularradio type pole array similar to those depicted in FIGS. 6 and 7 of U.S.Pat. No. 5,563,610 to Reudink. In one configuration, passive microwavedetector antenna arrays 2001 for detecting black body and spectral lineemission can be placed outside the walls, i.e., so that they can be seenby persons within the room. These can monitor across the entiremicrowave spectrum from 0.5 to 1000 GHz, or, for example, 3 GHz to 1000GHz. For example, to detect the HCl radical spectral line, a detectormounted on the wall is preferable as black body or spectral lineradiation is blocked by objects in its path. Alternatively, as notedabove, microwave radiation (for example, drywall, brick, block or adobe)at, for example, 0.5 to 3 GHz can penetrate non-metallic walls, andtherefore one or more of the detector antennas 2001 a to 2001 f can alsocan be placed within the walls. Placing the passive microwave detectorswithin the walls can be aesthetically desirable, but more significantly,can be advantageous in that an intrusion detection system with detectorsplaced within the walls of an enclosure cannot be seen or tampered withby an intruder, thus providing additional protection. Moreover, the wallmay provide some insulation value in the presence of a fire such thatreadings from such a detector may not be susceptible to fire whencompared to a detector mounted on the wall. A further embodiment maycomprise both inside the wall and outside the wall passive microwavedetectors.

Also as shown in FIG. 2, the plurality of detector antennas 2001 a-2001f can be arranged to detect radiation from different directions 2005a-2005 g. Each antenna array 2001 a-2001 f may have a primarydirectional lobe covering from a wall which it faces to a center of theroom. Two corners of a room may provide sufficient directionality todetermine the precise location of a fire or intruder in a room. Windowor door detectors 2001 e, f may be directed across the opening fordetection of fire cross-over or intrusion into the protected spacewithin the depicted room. In addition, as discussed above, one of theantenna arrays may be configured to receive microwave radiation at onefrequency band, for example, the 1.420 to 1.427 GHz 27 MHz pass band ofinterest for hydrogen line emission, while another of the arrays can beconfigured to receive microwave frequencies in the 1.200-1.900 GHz bandincluding the 1.420 to 1.427 GHz band of interest and the severalhydroxyl lines appearing between 1.612231 and 1.720530 GHz (and theirDoppler effects). Reference detector 2003 can be configured to detectradiation from a baseline reference source such as a wall, the ceiling(also serving as the floor above) or the floor. The omni-temperature HClspectral line can be passively captured at 620-630 GHz and its Dopplereffect observed. The radiation detected at detector antennas 2001 a-2001d can be compared with the baseline radiation detected by referencedetector 2003 from direction 2007 and processed as discussed in moredetail herein to provide detection of a fire or intruder within theenclosure 2009. Spectral line emission for hydrogen or hydroxyl radicalsin the microwave range can be evidence of a very hot fire.

Another exemplary configuration of detector antenna arrays is shown inFIG. 3. As shown in FIG. 3, a plurality of detector antenna arrays 3001a-3001 d can be placed in spaced-apart locations around a perimeter ofan out-of-doors space to be monitored such as a parking lot, collegecampus, hazardous waste dump, or storage facility. As with the detectorantenna arrays described above with respect to FIG. 2, the plurality ofdetector antennas 3001 a-3001 d can be arranged to detect microwaveradiation from different directions 3005 a-3005 d, at differentmicrowave frequencies, or both. In addition, as with the indoorconfiguration described above with respect to FIG. 2, reference detector3003 can be configured to detect passive microwave radiation for blackbody and spectral line emission from a baseline reference source fromdirection 3007 such as the ground, the sun, or foliage of large trees.The microwave radiation passively detected by detector antennas 3001a-3001 d can be compared with this baseline black body or expectedspectral line emission radiation, its Doppler effect detected andshedding frequency of a fire to provide detection of a fire or intruderwithin the perimeter defined by the antenna installation.

FIG. 4 depicts an exemplary configuration of detector antenna arraysalong a boundary such as a road, border, walkway, canal, etc. In thisembodiment, microwave detection in accordance with aspects herein can beparticularly useful for intrusion detection, since the presence of abody or a fire crossing the boundary can be almost instantaneouslydetected by the use of passive microwave detection of black bodymicrowave emission across a microwave spectrum with characteristicincreasing emission with increasing frequency (decreasing wavelength).As shown in FIG. 4, two or more detector antenna arrays such as arrays4001 a and 4001 b can be placed at spaced apart locations around theboundary to be protected, for example, at opposite ends of a linedemarcating the boundary. As with the detector arrays described above,detector arrays 4001 a and 4001 b can be configured to passively detectmicrowave radiation from directions 4005 a and 4005 b, at differentmicrowave frequencies, or both frequencies or frequency ranges. Themicrowave radiation so detected can be compared to baseline radiationdetected by reference detector 4003 in direction 4007 to provideimmediate indication of the presence of an intruder at the boundary. Aswill be discussed further herein, a Doppler effect detection of passivemicrowave frequencies can demonstrate movement of an intruder within aprotected space or movement of a fire by its spectral line emissionmovement. Also, shedding frequency detection can be compared with amoving fire shedding frequency signature (fire velocity).

In an embodiment as shown in FIG. 5A, a passive microwave fire detector5001 a having a directionality 5003 a can be incorporated into a devicethat can be held by a user to detect microwave radiation emanating froma fire or other thermal event such as a non-flaming hot spot. In anembodiment such as is shown in FIG. 5B, one or more passive microwavefire detectors 5001 b-5001 d, either alone or combined with conventionalsmoke, temperature, or fire detectors, can be incorporated into devicesthat can be worn by fire fighting or investigative personnel, such as onthe front 5001 b or back 5001 c of a protective overcoat and/or mountedon a helmet 5001 d. These antennas can have respective directionalities5003 b-5003 d to enable the wearer thereof to detect passive black bodyand spectral line microwave radiation in several different directions atonce. They may passively detect at all microwave frequencies across anentire 0.5 to 1000 GHz spectrum, for example, including any passivemicrowave HCl radical spectral line. In some embodiments, a conventionalpressure pinhole camera may be added to the helmet and provide a visualdisplay through smoke since microwave may penetrate smoke to provide amore visible indication to the firefighter of the contents of a roomexperiencing a fire. In some embodiments, a microwave radiationdetection device in accordance with aspects described herein can includean antenna proximate to the body to provide a stable referencetemperature against which to measure the thermal radiation of a fire.Such a reference requires no power to generate in contrast to apredetermined temperature source. In some other embodiments, a globalpositioning system (GPS) apparatus can be incorporated into a firstresponder's protective gear, and can be used to provide a guideregarding a building plan or layout, for example by using a map storedin central processing unit 8009 memory, or memory associated therewith,shown in FIG. 8. For example, a helmet may be provided with a displayfor wireless guiding data transmitted from signal processor 1005 andthus, for example, a first responder may be guided to door openings andgo directly to a detected fire victim that the first responder would nototherwise see but for passive microwave detection apparatus inaccordance with aspects described herein.

Such wearable or hand-held passive microwave fire detectors of FIG. 5can also enable such first responders to detect the presence ofnon-flaming “hot spots” to ensure that a fire is fully extinguished, orcan identify the presence—or absence—of persons or other living beingsin a space before entrance into the space (by seeing through walls) sothat fire fighters do not have to go into dangerous situations to rescuepersons who are in fact not there. In addition, a passive microwavedetector worn on a helmet of a first responder can serve as an earlypredictor of increasing threats of fire development and spread. Theseconditions occur when increasing levels of thermal heat transfer fromthe fire build up near the ceilings of the room causing items beneath toignite. During extremely high thermal radiation to the floor level(approximately 20 kW per square meter), the simultaneous ignition ofthese items results in a condition also known as “flashover.” Apredictive early warning of these increasing hazardous conditionsthrough black body and/or spectral line emission, Doppler effect orshedding frequency detection could enable first responders and firefighters to evacuate both themselves and other building occupants to asafer location before such a fire event occurs. This embodiment also canbe very useful for fire investigators who conduct on-scene assessmentsof post-fire smoldering debris to assist them in locating additionalareas for investigation at the scene or for fire investigators whenidentifying and confirming multiple sources of ignition duringfull-scale fire tests, particularly during the generation of opticallydense smoke. In addition, it may be possible to identify the nature ofthe burning material based on its several microwave “signatures” (blackbody, spectral line, Doppler effect and shedding, flicker or pufffrequency) and thus such a passive microwave detector when worn by afirst responder can assist him or her in identifying the nature of thefire and in formulating an appropriate plan for fighting it.

Components for use by such fire investigators may be designed to includeelectronic components operable without distortion at high temperaturessuch as 200° Fahrenheit (93° C.).

FIG. 6 depicts an exemplary embodiment of a multi-sided fire andintrusion detection apparatus comprising a detector array having aplurality of sets of passive microwave receivers and antennas 6001 a,6001 b . . . 6001 n, where n is the number of sides in the apparatus.The passive microwave radiation detected by these receivers is comparedto the radiation detected by reference detector 6003 which can be placedat a top side of the apparatus as shown in FIG. 6. This embodiment of apassive microwave fire and intrusion detection apparatus can be ineither a stationary or portable configuration and can be used to providefire and intrusion detection in locations such as along fence lines orhighways; in parking lots, hazardous waste dumps, at chemical sites, orshipyards; or on fire towers on mountains or hilltops. Because microwaveradiation travels through the air and therefore can be detected by anapparatus such as illustrated in FIG. 6 placed atop a fire tower at anelevated location, potentially catastrophic wildfires can be quicklydetected and treated before they become a danger to livestock, humanlife, or property via black body, spectral line emission, Doppler effectand/or shedding frequency detection alone or in conjunction with otherfire sensing apparatus such as visual and infrared or ultravioletdetection.

The output of the antenna arrays in a microwave fire and intrusiondetection system, whether in any of the configurations discussed aboveor otherwise, can be fed to a superheterodyne receiver shown in FIG. 7.As shown in FIG. 7, a superheterodyne receiver with a signal amplifiercan comprise an amplifier 7001, for example, a conventional low noiseblock amplifier or low noise amplifier possibly requiring a bandpassfilter having superior noise performance, a mixer 7003, and a localoscillator 7015 for demodulating the received signal (up to 1000 GHz) toan intermediate frequency (IF) signal, for example, in the 100 MHz to0.5 to 2.5 GHz range. The IF signal may then be amplified at amplifier7005 and transmitted by wired or wireless means to a signal processor1005 at a central site as shown in FIG. 1 for further processing andcompared with stored data in memory for an identified site (room,protected area or the like) and with characteristic spectral line orblack body emission characteristics data.

The signal processor 1005 shown in FIG. 1 at a central site may compriseelements 7007-7013 shown in FIG. 2. At the central site, the received IFsignal may be detected as a voltage and associated frequency orfrequency range at detector 7007, provided to a video amplifier 7009 andintegrator 7011 for integrating the baseband signal across the band ofinterest, and displayed at display 7013.

The output of the amplified signal, also referred to herein as abrightness temperature signal, may be interfaced to a laptop computer orsmaller computer, via a digital signal processor such as a Motorola DSP56800 discussed above, such as a personal hand-held or worn computer. Insome embodiments, such a computer can include a display for displaying avoltage reading/frequency which is converted to a temperature or adigitally sampled spectral line frequency and temperature and calculatedDoppler shift and/or shedding frequency. If radiation is emitted incertain predetermined spectra, for example, hydrogen chloride, hydrogen,hydroxyl radical, silicon dioxide or nitrogen dioxide, ammonia, water,carbon monoxide or other passive microwave detection spectra may beidentified in conventional manner, especially if present in sufficientquantity (which problem is mitigated if the spectral line emitted is notbeing used for active microwave transmission and signal to noise ratioimproved thereby). Hydrogen and hydroxyl presence can also be anindicator of high fire temperature. Such information can also beconveyed to first responders so that they can identify the nature of theburning materials and formulate the most effective plan for fighting thefire.

FIG. 8 provides a schematic of an electric circuit that can be used witha superheterodyne microwave receiver in accordance with one or moreaspects described herein. As shown in FIG. 8, an intermediate frequency(IF) amplifier 8001 may be tuned for the receive frequencies of pluralantenna arrays operating at frequencies between 0.5 and 1000 GHz and maymatch impedances for optimum transmission of data regarding passivelydetected temperatures (voltages). The output of such an IF amplifier8001 can be fed via a transformer (which can perform impedance matching,isolation and other functions) to a detector 8003 such as a 50 Hz to a0.5 to 2.7 GHz range analog detector circuit such as Analog Device AD8362 circuit 330, which may be likewise tuned to either a specificfrequency (such as that of an expected spectral line) or frequency range(for example for black body emission characteristic detection).Referring briefly to FIG. 20, such as frequency range as 0.5 to 3 GHzmay be useful for in-the-wall or through-the-wall passive microwave fireand intrusion detection. Its output in turn can be provided to circuitry8005 which includes a reference source voltage, for example, an LT1461-5circuit 340 for providing a reference voltage of five volts for use at aLTC 2400 analog to digital converter 8007. The digital output of A/Dconverter 8007 can be provided to a CPU 8009 for conversion into, forexample, ASCII for data entry into a signal processing unit computer1005 and memory 1013 shown in FIG. 1. The depicted CPU is onemanufactured and known as a PIC16F628 microcontroller but any suitableCPU can be used. The output of CPU 8009 can be provided to aconventional serial driver 8011 (for example, a 232° C.) for serialinput to a signal processor/memory 1005/1013. In this manner, the outputmay be temperature compensated (via the Dicke switch) for a referenceinput and then fed to a central processing unit for analysis and, forexample, display. Such a circuit may provide one input of many to signalprocessor 1005 shown in FIG. 1.

FIGS. 9-18 depict various aspects of testing of a passive microwavereceiver apparatus by the inventors hereof. As shown in FIGS. 9-12 and14, testing was performed using a small (approximately 19-inch)parabolic dish antenna, but it should be noted that such a parabolicantenna is only one or many antenna types that can be used in accordancewith aspects described herein, and that other antenna configurationssuch as flat arrays, horn type arrays, point antennas, or directionalantennas such as cellular telecommunication pole antenna arrays can beused.

FIG. 9 is a photograph depicting the use of a light source, here alantern, by one of the inventors hereof to aim a microwave receiver ontothe location of the test fires. The light source, while emitting lightin the visible part of the electromagnetic spectrum, also emitsmicrowave radiation which can be detected by the parabolic antenna shownin the photograph. In the present photograph, a two-bulb portablebattery-powered fluorescent lamp was used, but in alternativeembodiments, other light sources, for example, a laser light source, canbe used to direct an antenna to a region of interest for more accuratelong-range out-of-doors environments.

FIG. 10 is a photograph depicting use of a microwave receiver to detecta flaming fire comprising burning shredded paper in a confined space, aswould occur in a typical trash can fire. FIG. 11 is a photographdepicting use of a microwave receiver to detect a flaming firecomprising isopropanol burning in a pan, as might occur in a chemicalfire having a flame and little smoke. FIG. 12 is a photograph depictinguse of a microwave receiver to detect a smoldering, i.e., non-flaming,fire comprising burning shredded paper, as might occur in a trash canfire before full ignition occurs and there is considerable smoke.

Both the burning and smoldering shredded paper were shown to be easilydetected due to increased amounts of blackbody radiation produced bythese fires. However, the flaming pan fire, since it generates lesssmoke and less amounts of blackbody radiation, would have been moreeasily discovered using conventional rate-of-rise temperature and/orflame detectors. Alternatively, such a fire may be detected by HClpassive microwave spectral emission detection, or, if sufficiently hot,by passive microwave detection of certain spectral lines such ashydrogen and the hydroxyl radical (and Doppler effect or sheddingfrequency detection).

Other testing was performed in a shielded steel building as shown inFIGS. 13 and 14. As noted above, microwave radiation does not penetratemetal walls and so the building acted, in essence, as a “Faraday cage”blocking out any external extraneous electric fields or electromagneticradiation. It thus could be ensured that any microwave radiationdetected by the inventors during their tests came from the fire and notfrom any sources outside the building. As shown in FIG. 14, a test firewas ignited and the antenna set up to monitor the fire during theignition, growth, steady state, and decay stages. A graph of the voltagereadings from this test fire is shown in FIG. 15. The voltage readingsindicate and track a steady increase of temperatures until its peakafter approximately 800 seconds, when the fire was then extinguished.

During the same testing as performed in a shielded steel building asshown in FIGS. 13 and 14, thermocouple temperature data was alsorecorded at the floor, ceiling, and directly above the burning object atapproximately 2 feet (0.61 meters) above the floor. This temperaturedata is shown in FIG. 16 as an overlay on the data previously shownvoltage data in FIG. 15. Note that this FIG. 16 shows a sharp increasein temperature after ignition, leveling off at approximately 1000degrees Fahrenheit (953 degrees Celsius), and quickly dropping afterextinguishment of the fire after approximately 800 seconds. Besides HClspectral lines at passive microwave frequency, some spectral emissionmay be detected at hydrogen and hydroxyl radical lines and black bodyradiation may be observed across a broad frequency spectrumcharacteristic of a flame of such a fire at many stages.

Further experimentation by the inventors demonstrates the use of passivemicrowave radiation detection in the field of intrusion detection viablack body emission. Testing by the inventors showed that approachingoverhead aircraft could be detected, either because it provided areflective interference easily detected by the apparatus because itemitted microwave (radar) energy that could be detected as a change involtage. For example, the scatter plot in FIG. 17 shows a positivescattered pattern of voltage readings that occurred when an aircraft wasrecognized over the horizon and flew over the test site at the time thereadings in FIG. 17 were being made. Since an application of microwavefire or intrusion detection may be subject to false alarms by spuriousaccidental or intentional jamming signals on or surrounding theoperational passive microwave frequency(ies) or frequency band(s),anomalies with known characteristics may be stored in central processingunit 1005 memory and subtracted or filtered from recorded measurement.Alternatively or in addition, the use of protected passive radioastronomy frequencies may ensure that few false alarms are triggeredwithout having to filter anomalous radiation from active known orunknown sources.

Similarly, testing by the inventors showed the usefulness of a microwavedetection apparatus as an intrusion detector via passive black bodymicrowave and Doppler effect detection. In particular, as shown in FIG.18, a human may be detected at 15 meters (50 feet) from an array orantenna element of pointed in their direction. As shown in FIG. 18, avoltage drop occurred when a human being passed within range of thedirectional microwave receiver. Negative voltage 1801 represents a humanat a relatively close distance to the detection apparatus while negativevoltage 1803 represents a person farther away showing movement of theindividual over time. The same sized person was detected at both points.Consequently, a person may be ranged by their size at signal processingapparatus 1005 and triangulation or other conventional methods used toprecisely locate such a person. It is to be noted that a human may bedetected as a negative voltage reading when compared to a referencevoltage reading and so may be distinguishable from a fire which isdetected by a positive voltage reading when compared with a referencevoltage. Depending on the circumstances, such a detected person may bean intruder or a fire victim, and consequently, an embodiment of apassive microwave detection system may have utility for both intrusiondetection and fire detection.

Referring now to FIG. 21, there is shown in FIG. 21A an exemplaryembodiment for capture of the hydrogen spectral line at 21 cm andassociated Doppler effect and shedding frequency characteristics. Asshown in FIG. 20, 1.420 GHz is one received frequency in the passivemicrowave region. A reception at 1.8 GHz can capture both the hydrogenline along with the hydroxyl radical collection of spectral lines whichindividually or together 1) can provide an indicator of a hot firetemperature and 2) are at a frequency that can be measured by a detectormounted in a wall per FIG. 1. A signal may be captured at between 100MHz and 1.5 GHz and high-passed at 1.4 GHz filter 2100. This output isthen low-passed at 1427 MHz at low-pass 2110. The output is then mixedat mixer 2120 with a 1427 GHz source and brought down to a baseband 27MHz pass band. This pass band is then band-pass filtered at filter 2140and, for example, the hydrogen line may be located and its Dopplereffect studied at detector 2150. Its flicker, puff or shedding frequencymay be detected at shedding frequency detector 2160 as a frequency thatmay show fire velocity, composition or location (for example, next to awall) as is known in the art (as well as serve as another fire“signature”). This same circuit may be applied in different form fordetection of hydroxyl radical, HCl or any other spectral line detectableby a passive microwave receiver designed to detect it present in a fire.Thus, for example, frequencies for both hydrogen and hydroxyl radicalcan be similarly detected by a single detector operating at, forexample, 2 GHz. In FIG. 21(B), similar reference numerals denote similarelements. The hydrogen line is again captured but the 27 MHz passband issampled across the 27 MHz spectrum for example to compare against apredetermined black body characteristic for this spectrum. Though thereis little variation between a human body and a fire at this frequency asto black body radiation, there is very large signal to noise ratiobecause there is no expected man-made noise at this frequency;consequently, small emission of H or OH may be quantified. By way ofexample, a plurality of filters each with a 3 MHz passband may capturechannels between 0 and 27 MHz within a 27 MHz spectrum. The circuit ofFIG. 21(B) could just as easily captured 0.5 to 3 GHz and comprise anin-the wall or through-the-wall detector for detecting a constantlyincreasing black body emission with increasing frequency in comparisonto a stored FIG. 19 for a human body or a fire (candle, gas or othercharacteristic fire) and one or the other thus distinguished by blackbody emission. On a broader scale, black body emission may be measuredby passive microwave detection from frequencies as low as 0.5 to 3 GHzfor in-the-wall or through-the-wall detection and 0.5 to 1000 GHz formounted on the wall black body or spectral line emission. Because of thesimilar front ends of the circuits of FIGS. 21(A) and (B), the analog ordigital signal processing of the captured frequency bands may beperformed remotely at a central processor 1005 shown in FIG. 1 and allexpected characteristics data stored in associated memory 1013.

Thus, it can be seen that passive detection of microwave radiation froma fire or other heat source such as a human, animal, airplane, orautomobile, can be used to provide fire and intrusion detection. Asystem of passive microwave detectors in accordance with aspects hereincan be used to monitor and protect property. Passive microwave detectorscan enable first responders to better identify and fight fires and tolocate and save the lives of persons trapped in a fire.

Although particular embodiments, aspects, and features have beendescribed and illustrated, it should be noted that the inventiondescribed herein is not limited to only those embodiments, aspects, andfeatures. It should be readily appreciated that modifications may bemade by persons skilled in the art, and the present applicationcontemplates any and all modifications within the spirit and scope ofthe underlying invention described and claimed herein.

For example, it should be noted that other frequencies within themicrowave range between 300 MHz and 1000 GHz, other combinations offrequencies including visible spectrum and infrared or ultraviolet imageprocessing, known smoke, ionization radiation, thermocouple and otherknown systems may supplement and provide variations in configuration andprotocol and should be deemed within the scope of the presentdisclosure.

In addition, some embodiments of a passive microwave fire and intrusiondetection apparatus may incorporate other conventional detectorsoperating inside and outside the microwave region, such as smokedetectors and temperature rise detectors and conventional intrusiondetectors using ultrasound emission and reception, for example, between20 KHz and 10 GHz. Such embodiments are also contemplated to be withinthe scope and spirit of the present disclosure.

1. A method for detecting at least one of a fire and an intruder usingpassive reception of microwave radiation, comprising: receiving a firstmicrowave radiation signal at a first receiver, said first receiverincluding a first antenna, a first frequency of said first receivedmicrowave radiation signal being indicative of a temperature of a sourceof said first microwave radiation; receiving a second microwaveradiation signal at a second receiver, said second receiver including asecond antenna, a second frequency of said second microwave radiationsignal being indicative of a temperature of a source of said secondmicrowave radiation, wherein said first and second frequencies arewithin a range of frequencies not being used for active transmission ina geographic area encompassing a location of said first and secondreceivers, a second range of frequencies being between 0.5 and 3 GHz forcapturing a hydrogen line and a hydroxyl radical line; storing a blackbox radiation frequency characteristic for a human body and for a firein memory of a central computer for said 0.5 to 3 GHz frequency range;and comparing said first frequency with said second frequency and withsaid black box radiation frequency characteristic to determine apresence of at least one of a fire and an intruder at said centralcomputer.
 2. The method according to claim 1, further comprising:transmitting said first and second microwave radiation signals to asignal processor; said first microwave radiation signal being convertedto a first voltage signal; said second microwave radiation signal beingconverted to a second voltage signal; said first voltage signal beingsubtracted from said second voltage signal to provide a resultingvoltage signal; and said presence of said at least one of said fire andsaid intruder being determined based on said resulting voltage signal.3. The method according to claim 2, wherein a presence of a fire can bedetermined if said resulting voltage signal is positive.
 4. The methodaccording to claim 2, wherein a presence of a living being can bedetermined if the resulting voltage signal is negative.
 5. The methodaccording to claim 4, wherein said negative resulting voltage signaldistinguishes a fire from a living being.
 6. The method according toclaim 1, wherein at least one of said first and second receivers isconfigured to receive frequencies in one of a range between 1.400 to1.427 GHz and 1.612231 to 1.720530 GHz.
 7. The method according to claim1, wherein at least one of said first and second frequencies is in arange between 300 MHz and 1000 GHz, the method further comprisingdetermining the presence of a spectral line for HCl within the range. 8.The method according to claim 1, said first receiver beingself-adjusting to compensate for a change in temperature of said sourceof said first microwave radiation signal.
 9. The method of claim 2,wherein at least one microwave radiation signal characteristic of afield of view of one of said first and second receiver is stored in amemory of said signal processor, said stored microwave radiation signalbeing subtracted from a received microwave signal to determine one of anintrusion into and a fire within said field of view.
 10. The method ofclaim 2, further comprising transmitting data via a wirelesstransmitter, the data representing an identity of at least one of saidfirst and second receivers and their location to said signal processor.11. A system for passive microwave detection of at least one of a fireand an intruder, comprising: a first receiver configured to detect afirst microwave radiation signal from a first source, a first frequencyof said first received microwave radiation signal being indicative of atemperature of said first source; at least one second receiverconfigured to detect a second microwave radiation signal from a secondsource, a second frequency of said second microwave radiation signalbeing indicative of a temperature of a source of said second microwaveradiation, said second frequency being indicative of the presence of oneof the hydrogen and the hydroxyl radical spectral line wherein saidfirst and second frequencies are within a range of frequencies not beingused for active transmission in a geographic area encompassing alocation of said first and second receivers; a signal processor, saidsignal processor being configured to receive said first and secondmicrowave radiation signals from said first and second receivers andbeing further configured to convert said first and second microwaveradiation signals to first and second voltages, respectively, saidsignal processor further being configured to subtract said secondvoltage signal from said first voltage signal to obtain a resultingvoltage signal; wherein a presence of a fire can be determined if saidresulting voltage signal is positive; and wherein a presence of a livingbeing can be determined if said resulting voltage signal is negative.12. The system according to claim 11, wherein at least one of said firstand second receivers comprises one of a point antenna, a flat antennaarray, a parabolic antenna array, a horn-type antenna array, and adirectional cellular telecommunication pole antenna array.
 13. Thesystem according to claim 12, wherein at least one of said first andsecond receivers comprises a telecommunication pole antenna array usedto send and receive cellular telecommunications signals.
 14. The systemaccording to claim 11, wherein at least one of said first and secondreceivers is configured to receive frequencies in one of a range between1.400 to 1.427 GHz, 1.612231 to 1.720530 GHz, and between 625 and 626GHz.
 15. The system according to claim 11, wherein said first and secondreceivers are configured to be placed in spaced-apart locations in awall of an enclosed space made of one of drywall, brick, block, adobeand concrete, at least one of said first and second receivers beingdirectional and providing a main lobe from a wall of said enclosed spaceto at least a center of said enclosed space.
 16. The system according toclaim 15, wherein at least one of said first and second receivers areconfigured to be placed within a wall of said enclosed space anddirected toward the center of an opening to said space comprising one ofa window, a gate and a door.
 17. The system according to claim 11,further comprising a display, said display being configured to showinformation regarding at least one of said fire or said intrudercomprising one of a visual representation of said space at a givenmicrowave frequency and a graph of microwave frequency versus spectralmicrowave frequency emission across a received microwave band.
 18. Thesystem according to claim 11, wherein said signal processor comprises asuperheterodyne receiver.
 19. The system according to claim 11, whereinsaid signal processor includes a memory, and further wherein at leastone microwave radiation signal characteristic of a field of view forsaid second receiver is stored in said memory, said stored microwaveradiation signal being subtracted from a received microwave signal toidentify at least one of a fire and an intrusion into said field ofview.
 20. The system according to claim 15, further comprising third,fourth, and fifth receivers, wherein each of said second, third, fourth,and fifth receivers is placed in or one a wall of said enclosed spaceand said first receiver is placed in a location in said enclosed spacewhereby a reference temperature signal may be received.
 21. A method fordetecting at least one of a fire and an intruder using passive receptionof microwave radiation, comprising: receiving a microwave radiationsignal at a receiver, said receiver including at least one antenna, afrequency of said received microwave radiation signal being indicativeof a temperature of a source of said microwave radiation, one frequencycomprising the frequency representing the hydrogen chloride spectralline and another frequency being in the frequency range between 0.5 and2.5 GHz, wherein said one or another frequency is within a range offrequencies not being used for active transmission in a geographic areaencompassing a location of said receiver; wherein said source of saidmicrowave radiation is one of black body emission and spectral lineemission from one of a fire and an intruder.
 22. The method according toclaim 21, further comprising: transmitting said microwave radiationsignal to a signal processor, said microwave radiation signal beingconverted to a voltage signal and being transmitted with its associatedfrequency or frequency range; said presence of said at least one of saidfire and said intruder being determined based on said voltage signal andfrequency or frequency range.
 23. The method according to claim 22,wherein a presence of a fire can be determined if said voltage signal ispositive.
 24. The method according to claim 22, wherein a presence of aliving being can be determined if said voltage signal is negative. 25.The method according to claim 24, wherein said negative voltage signaldistinguishes a fire from a living being.
 26. The method according toclaim 21, wherein said receiver is configured to receive a passivemicrowave radiation signal representing one of the hydrogen and hydroxylradical spectral line.
 27. The method according to claim 22, whereindata representing at least one microwave radiation signal is stored in amemory of said signal processor, said stored microwave radiation signalbeing subtracted from said received passive microwave radiation signalto determine a presence of at least one of a fire and an intruder insaid field of view.
 28. An apparatus for passive microwave detection ofat least one of a fire and an intruder, comprising: a receiverconfigured to detect a microwave radiation signal from a first source, afrequency of said received microwave radiation signal being indicativeof a temperature of said first source, said frequency being within arange of frequencies not being used for active transmission in ageographic area encompassing a location of said receiver including thehydrogen line at 21 cm and the hydroxyl line within a frequency rangefrom 1.612231 to 1.720530 GHz; an antenna configured to passively detecta microwave radiation signal from a predetermined source, the apparatusbeing self-adjusting for changes in temperature of the predeterminedsource; and a signal processor configured to compare said receivedmicrowave signal to said microwave signal from said predetermined sourceto provide a resulting voltage signal; and a memory for storing a blackbody emission characteristic for passive microwave reception across aportion of the microwave spectrum; wherein a presence of at least one ofa fire and an intruder is determinable from said resulting voltagesignal via comparison with said black body emission characteristic data.29. The apparatus of claim 28, wherein said apparatus is configured tobe one of a hand-held device, worn by a person or a vehicle.
 30. Theapparatus of claim 28, wherein said apparatus is configured to be wornby a user and said predetermined source comprises a part of a humanbody.
 31. The apparatus of claim 28, further comprising a transmitterconfigured to wirelessly transmit information regarding said passivelydetected microwave signal and its frequency to a remote signal processorfor processing.
 32. The apparatus of claim 28, wherein said receiver isconfigured to receive frequencies in a further frequency range includinga microwave spectral emission of HCl.